1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#define PUSHBACK_MAX 10
typedef struct {
FILE* stream;
int pushback[PUSHBACK_MAX];
int pushback_ix;
} StreamWithPushback;
StreamWithPushback swpb_new(FILE* f) {
StreamWithPushback ret;
ret.stream = f;
ret.pushback_ix = 0;
for (int i=0; i<PUSHBACK_MAX; i++) {
ret.pushback[i] = -1;
}
return ret;
}
int getch(StreamWithPushback* swpb) {
if (swpb->pushback_ix > 0) {
int ch = swpb->pushback[swpb->pushback_ix];
swpb->pushback_ix--;
return ch;
}
return getc(swpb->stream);
}
void ungetch(StreamWithPushback* swpb, int ch) {
if (swpb->pushback_ix >= PUSHBACK_MAX) {
fprintf(stderr, "pushback buffer was full!\n");
exit(1);
}
swpb->pushback[swpb->pushback_ix] = ch;
swpb->pushback_ix++;
}
/* getint: get next integer from input into *pn */
int getint(StreamWithPushback* swpb, int *pn) {
int c, sign;
while (isspace(c = getch(swpb))) {}
if (!isdigit(c) && c != EOF && c != '+' && c != '-') {
ungetch(swpb, c);
return 0;
}
sign = (c == '-') ? -1 : 1;
if (c == '+' || c == '-') {
c = getch(swpb);
// If c isn't then a digit, then we don't have a number.
if (!isdigit(c)) {
ungetch(swpb, c);
// Push the sign character back as well, don't consume it
ungetch(swpb, sign == -1 ? '-' : '+');
return 0;
}
}
for (*pn = 0; isdigit(c); c = getch(swpb)) {
*pn = 10 * *pn + (c - '0');
}
*pn *= sign;
if (c != EOF) {
ungetch(swpb, c);
}
return c;
}
#ifndef test
int main(void) {
int p, x;
StreamWithPushback swpb = swpb_new(stdin);
while ((x = getint(&swpb, &p)) != EOF) {
if (x > 0) {
printf("%d\n", p);
} else {
printf("not a number!\n");
}
}
}
#else
#include "CuTest.h"
// I could write unit tests here, using fmemopen
// instead of reading something off the filesystem.
// But I can't be bothered.
#endif
|
